# Python3 program to find the smallest window 
# containing all characters of a pattern. 
no_of_chars = 256

# Function to find smallest window 
# containing all characters of 'pat' 
def findSubString(string, pat): 

	len1 = len(string) 
	len2 = len(pat) 

	# check if string's length is less than pattern's 
	# length. If yes then no such window can exist 
	if len1 < len2: 
	
		print("No such window exists") 
		return "" 

	hash_pat = [0] * no_of_chars 
	hash_str = [0] * no_of_chars 

	# store occurrence ofs characters of pattern 
	for i in range(0, len2): 
		hash_pat[ord(pat[i])] += 1

	start, start_index, min_len = 0, -1, float('inf') 

	# start traversing the string 
	count = 0 # count of characters 
	for j in range(0, len1): 
	
		# count occurrence of characters of string 
		hash_str[ord(string[j])] += 1

		# If string's char matches with 
		# pattern's char then increment count 
		if (hash_pat[ord(string[j])] != 0 and
			hash_str[ord(string[j])] <=
			hash_pat[ord(string[j])]): 
			count += 1

		# if all the characters are matched 
		if count == len2: 
		
			# Try to minimize the window i.e., check if 
			# any character is occurring more no. of times 
			# than its occurrence in pattern, if yes 
			# then remove it from starting and also remove 
			# the useless characters. 
			while (hash_str[ord(string[start])] > 
				hash_pat[ord(string[start])] or
				hash_pat[ord(string[start])] == 0): 
			
				if (hash_str[ord(string[start])] > 
					hash_pat[ord(string[start])]): 
					hash_str[ord(string[start])] -= 1
				start += 1
			
			# update window size 
			len_window = j - start + 1
			if min_len > len_window: 
			
				min_len = len_window 
				start_index = start 

	# If no window found 
	if start_index == -1: 
		print(-1) 
		return "" 
	
	# Return substring starting from 
	# start_index and length min_len 
	return string[start_index : start_index + min_len] 

# Driver code 
if __name__ == "__main__": 
    for i in range(int(input())):
        string = input()
        pat = input()
        print(findSubString(string, pat)) 
